Development and growth of selected speech perception and speech production skills will be evaluated and compared in three separate groups of profoundly deaf children who wear cochlear implants, vibrotactile aids, or conventional hearing aids. A repeated- measures design will be used in which each subject will serve as his own control. Children in the three groups will be matched on relevant medical, audiological, and educational variables. Each child will be enrolled in an individualized aural (re)habilitation program throughout the three-year study, and efforts will be made to ensure that subjects in each group receive comparable exposure to their sensory aids. Experiments will be aimed at assessing the relative potential of each device to: (1) enhance suprasegmental and segmental features of speech, (2) alter the primary modality (acoustic vs. visual) used for the perception of speech, (3) supplement lipreading skills, (4) increase attention to task, and (5) aid in the production and intelligibility of the children's speech. Results from the project are expected to facilitate early and effective intervention for acquisition of receptive and expressive communicative skills in deaf children, and to have implications for selection and training strategies and the design of sensory aids for all profoundly hearing-impaired children.